Setting up four subwoofers

[olds1959special]

With the HPF filters removed completely, and adding a parametric EQ at 40Hz and 75Hz, 0.5 BW, and -7 and -6 dB respectively, with the top subs set to 90Hz LPF and the bottom subs set to 130Hz LPF, I was able to get this:

It seems there is less of a dip in the upper bass region, and for some reason the highs look better now.

btw, I am using them stacked in a L/R setup because I don't have space to put the subs anywhere else. Also, I like stereo bass.

I'll be trying the MMM soon.

View attachment 499800

I'm still listening to this setup, and still wondering if what I'm doing is okay. I'm running the speakers full-range, but I really don't think they have a lot of very low bass (JBL L890's). Then I'm playing the subs full-range, or at least as high as the LPF will go (90Hz and 130Hz). Then I EQ down the peaks in the bass at 40 and 75Hz which are from the room as I explained in my previous post. I don't have a problem with the sound but not sure if it's technically okay.

 

[levimax]

I'm still listening to this setup, and still wondering if what I'm doing is okay. I'm running the speakers full-range, but I really don't think they have a lot of very low bass (JBL L890's). Then I'm playing the subs full-range, or at least as high as the LPF will go (90Hz and 130Hz). Then I EQ down the peaks in the bass at 40 and 75Hz which are from the room as I explained in my previous post. I don't have a problem with the sound but not sure if it's technically okay.

There are two potential problems running the main speakers full-range. The first is you give up the advantage of high passing the mains i.e. less distortion especially IM distortion at LF and high SPL. The second is that often times you can get "cancelling" of the sub output by the mains output due to room issue or group delay differences, so rather than more bass you can end up with less bass (or big dips). Since this cancellation effect is a time domain issue you can't predict it by looking at the individual magnitude responses, you would have to measure both a high passed response and a full-range response an see what looks and sounds better to you. If the full range looks and sounds better there is nothing wrong with going with it.

 

[olds1959special]

At least for now I found running both subs at 90Hz LPF (instead of one pair at 130Hz) sounds better and shouldn’t interfere with the EQ since that’s happening below 90Hz.

 

[levimax]

At least for now I found running both subs at 90Hz LPF (instead of one pair at 130Hz) sounds better and shouldn’t interfere with the EQ since that’s happening below 90Hz.

You can't really be sure what is happening unless you take some measurements, 2 drivers playing at the same frequency at the same time are going to interact differently when a crossover is added and it may act as you think it will or it may not.

 

[DVDdoug]

I'm NOT an expert on this subject but you should be able to find some guidelines for multiple subwoofer placement. And since not all rooms are simple rectangles and not all placements are practical or possible, I assume there is simulation software that can accommodate those situations.

Multiple sub placement optimization will probably eliminate the possibility of stereo subs...

Of course you can experiment and make measurements with various placements, then improve it further with apply EQ or room correction or MSO.

I have something that I copied from Floyd Toole's book for TWO subs but I don't remember if there's anything in the book for four:

 

[olds1959special]

Unfortunately there are no possible places for me to put the subs anywhere else than where they are because of space limitations.

I started thinking setting the LPF to the lower (lowest) settings of 60Hz (and 65Hz, easy to set on the S10 V2 subs) makes more sense with the mains running full range, which probably start to roll off about 60Hz. This should prevent unnecessary overlap of sound. I measured after I did this and found I still needed the same EQ settings because they are based on the build up of bass from the room itself. So now I’m listening this way.

Edit: oops, had 1 sub at 90Hz by mistake, have to remeasure.

for now, I turned off the EQ. My phone app says the room response curve is not that bad this way anyway.

I also tried to gain match the subs by holding my SPL meter directly in front of each one and then adjusting.

It’s probably better not having to do the extra audio processing with Sound Source…

I’ll remeasure and post new results soon. But it seems to sound good this way.

 

[jmdesignz2]

It’s not complicated, I don’t think, I like stereo bass and auditory envelopment, as well as a controllable bass boost, and it sounds the best now I think, going “double-bass” with no crossover, but then adjusting for the most offensive peaks from room modes. SoundSource does the job with its PEQ.

I’m running all four subs at their highest possible LPF setting (90Hz and 130Hz) and have them gain-matched.

The four 10” subs are just big enough to fit right next to the speakers and not get in the way of the room too much, like a larger sub would, and since they are powered I don’t need any more amps.

I went through something similar. I was not happy with my bass response. I purchased a THX rated 15in 1kw sub and still was not happy. I considered getting a second sub...or more powerful amps.

but then I added a single corner bass trap (DIY $150) and the difference was transformational. Now I have no desire for a second sub or amps or any other speakers

the difference in bass resolution, bass, lower mid range etc is incredible. Sounds as good as / better than my Hifiman Edition XS headphones

 

[olds1959special]

Before EQ. The top pair of subs (KRK S10.4) are calibrated with the nominal gain setting on and the dial turned one big notch away from the maximum. It's a precise, stepped adjustment pot so I know both subs are exactly the same. The LPF is set to 60Hz. The bottom pair are set to 65Hz (just because it's easy to set it to that based on the dial, which is not stepped, but this way it's at a straight angle.) I'm clearly seeing the 40Hz peak again.

So I used Sound Source 2 (I got the new version) and applied this EQ filter:

These are the results after EQ:

 

[olds1959special]

I also decided to lower the bottom pair of subs to 50Hz, the lowest setting, so that I know they are both exactly the same, and also since the mains should be down by 3dB at 50Hz. This is a frequency response chart for my JBL L890's running full-range. (from soundstage.com)

I think it’s sounding the best now, at least without a crossover. I -could- always use the subs crossovers but I’m trying to avoid that.

 

[audiofooled]

For me, stereo bass and AE is the way to go. However, for the best results, addressing your room resonances and time domain performance is very important. This is also where things tend to get a bit complicated.

Help me understand Impulse Response, Step Response, and Time Alignment

I have 4 subs, 2 SVS SB3000 which are 13" small sealed heavily DSP'd subs and 2 very large 18" DIY seal subs with no DSP. I have tried to use these in a 4 sub set up but was never happy with the integration. I tried DIRAC DLBC, 2 different MSO programs, REW Time Alignment tool, REW wavelet...

www.audiosciencereview.com

Smooth magnitude response, IME, comes as a result, and from there finally you can make it flat, or whatever, to your preference. It's rarely the other way around, in rooms.

 

[jmdesignz2]

looks like you have a huge null that starts around 200 thru 325hz? Also a big one around 80-90hz. Those are similar to what I had in my system which were all but cured with less than $250 of acoustic DIY panels and the $150 DIY corner bass trap. I would also expect the 10 to 30hz range would improve as well as the 40hz peak would be tamed.

 

[olds1959special]

In the end I decided this didn't sound good so I got rid of the additional 2 subs (the older pair) and moved them somewhere else.

 

[jmdesignz2]

In the end I decided this didn't sound good so I got rid of the additional 2 subs (the older pair) and moved them somewhere else.

Did you try a corner bass trap DIY? Would really recommend this as it resolved so many issues in my system AND the phase looked much better as well. The measured and audible difference was dramatic.

The room is a huge part of how speakers will perform and I have not seen any info on your room dimensions, pictures?

 

[olds1959special]

Did you try a corner bass trap DIY? Would really recommend this as it resolved so many issues in my system AND the phase looked much better as well. The measured and audible difference was dramatic.

The room is a huge part of how speakers will perform and I have not seen any info on your room dimensions, pictures?

I would love to treat my room but this is not possible due to sharing the space with others who would not tolerate that. lol

Changing from four subwoofers to two in this configuration, is not going to make much of a difference, provided I turn up the gain to compensate.

I'm using the newer KRK S10.4's now which go lower and are cleaner, so adding two subs ended up still being an upgrade.

The KRK S10 V2's got relegated to make full-range speakers in my other setup, by running them with a pair of Yamaha MSP5 V2's through the crossover at 80Hz. I just put the speakers directly on top of the sub, positioned towards the front.